Suspicious that marijuana was being grown in Danny Kyllo's home, federal agents used a thermal imaging device to scan his home from a public street. The agents sought to determine whether the amount of heat emanating from Kyllo's home (which was part of a triplex) was consistent with the amount emanated from high-intensity lamps typically used for indoor marijuana growth. The scan showed that Kyllo's roof and a side wall were relatively hot compared with the rest of his home and substantially warmer than the neighboring units. Based in part on the thermal imaging results, a federal magistrate judge issued a warrant to search Kyllo's home, where the agents found marijuana growing. After being indicted on a federal drug charge, Kyllo unsuccessfully moved to suppress the evidence seized from his home. He then entered a conditional guilty plea under which, on appeal, he could challenge the use of the thermal imaging device and the validity of the resulting warrant. The government took the position that the use of the device, when operated from a public street, was not a search for purposes of the Fourth Amendment and that Kyllo therefore did not have a basis for his Fourth Amendment based challenge. Was the government correct in this argument?